Method of manufacturing uniformly-loaded conductors



Aug. 31 1926. 1,598,452

E. SCHURER METHOD OF MANUFACTURING UNIFORKLY LOADED CONDUCTORS Filed August 13, 1925 7mgmetmble stnp copper 7 I a] C Fig. Z.

67 Sum 'Patented Aug. 31', 1926.

UNITED STATES I i r 1,598,452 {PATENT OFFICE.

EU GEN SCH'UREB, 0F COLOGNE-MULHEIMI GERMANY, ASSIGNOR '10 FELTEN AND GUIIJLEAUME CARLSWERK ACTIEN GESELLSCHAFT, OF COLOGNE-MULHEIM, GER- METHOD 0] mUFACTUBING UNIFORMLY-LCADED CONDUCTOBS.

Application filed Augult 13, 1925, Serial No. 50,144, and in Germany September 1, 1924.

It has been found necessary when manufacturing uniformly loaded conductors used for signalling purposes, in which the loading material has to be'annealed for the purpose of improving its magnetic properties in the case of small magnetizing-forces, to arrange that the loading strip shall not be annealed until it has been applied to the actual conductor, because otherwise the magnetic properties of the loading material would be detrimentally affected by the mechanical infiuences exerted when the conductor is being wound. Even when this method is adopted,

7 special additional measures must be taken in order to obtain a loading material with the best possible magnetic properties. As the heat expansion coeflicient of the materials from which the loading strip is usually made is smaller than that of copper and in' the annealing processes hitherto adopted, the

copper has been heated at the same time, the full eflect of the annealing was not obtained owing to the tension caused in the loading strip as a result of the copper expanding to a greater extent. I

In order to obviatethis drawback it has already been proposed, to interpose a thin layer of material containing carbon, such as for example pa er, when winding the loading strip on to t e actual conducton. By this means when the conductor is annealed, the burning of the layer causes sufficient space to be left for.the copper to expand, thus avoiding tension in the loading strip.

This method has the disadvantage that the magnetizable materials may absorb carbon. If this drawbackis avoided by substituting a'layer of inorganic substance for that containing carbon, the material forming the layer combines with the copper or the magnetizable substance thus affecting the mechanical and electrical properties of the conductor.

According to the present invention a different method is adopted for obtaining the space required for the expansion of the copper, between the copper conductor and theloading strip. In. this case before the load-.

ing strip is wound onto the copper line, the latter is coated with a layer of a lac which hardens uniformly, dissolves completely in certain solvents, and the thickness of which corresponds to the required space. The loading strip is then wound on over the layer of lac, whereupon after the winding, .it is placed in a liquid which dissolves the lac and is then annealedin a known manner.

Figure 1 of the accompanying drawing illustrates a continuously loaded conductor according to the present invention. a is the copper conductor, b the layer of lac and 0 the loading or magnetizable strip. Figure 2 illustrates the same conductor after the lac has beemdissolved bv the solvent.

There are a great number of lacs which can be used for this purpose, for instance: (1) Shellac-'colophony lac consisting of 200 grsrshellac, 150 grs. colophony, 650 grs. spirit. p

(2) Celluloid lac, con isting of (a) 200 grs. acetyl cellulose, 800 grs. acetone, or-(b) 100 grs. celluloid, 300 grs. amyl acetate, 300 grs.

acetone, 300 grs. ether, to which grs. camphor may also be added.

The lacs can be completely, removed again with the solvents employed, that is to say the lac referred to under 1) can be removed by means of spirit, that under (2a) by means sitlon inside the loading strip. These additions may for instance be fine, short asbestos fibres, mica powder and the like.

lVhat I claim is:

1. A method of n'lanufacturing uniformly loaded conductors for signalling purposes, consisting in coating the conductor with a layer of lac which hardens in a uniform manner, is'soluble in certain solvents and is of a suitable thickness, winding the loading strip over the conductor coated with the said layer then placing the conductor in a liquid which dissolves the lac and finally annealing the conductor and loading strip.

2. A method of manufacturing uniformly loaded conductors for signalling purposes, consisting in coating the conductor with a layer or lac, comprising substances which dissolve in certain solvents and small amounts of insoluble and. incombustible substances, the lac hardening in a uniform manner and being of a suitable thickness, winding the loading strip over the conductor coated with the said layer, placing the conductor in a liquid which dissolves the soluble parts of the lac, the other substances remaining between the loading strip and the conductor and finally annealing the eonductor and loading strip for the purpose set 10 forth.

In testimony whereof Ihave signed my name to this specification.

EUGE'N SCHURER. 

